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A die, commonly used in press-brake forming, that is machined horizontally with a square or rectangular cross-sectional opening that provides two edges over which metal is drawn into a channel shape.
A direct extrusion process for metals that uses molten glass to insulate the hot billet and to act as a lubricant.
The elongation at rupture.
The maximum stress (tensile, compressive, or shear) a material can sustain without fracture; determined by dividing maximum load by the original cross-sectional area of the specimen. Also known as nominal strength or maximum strength.
ultimate tensile strength
The ultimate or final (highest) stress sustained by a specimen in a tension test.
ultrahard tool materials
Very hard, wear-resistant materials–specifically, polycrystalline diamond and polycrystalline cubic boron nitride–that are fabricated into solid or layered cutting tool blanks for machining applications.
Structural steels with minimum yield strengths of 1380 MPa (200 ksi).
Machining processes used to alter surface characteristics such as finish, waviness, roundness, etc., with substantial removal of the work material. Examples include lapping and polishing of optical lenses, computer chips, or magnetic heads, and honing of cylinder liners.
A beam of acoustical radiation with a frequency higher than the frequency range for audible sound–i.e., above about 20 kHz.
Immersion cleaning aided by ultrasonic waves that cause microagitation.
A frequency, associated with elastic waves, that is greater than the highest audible frequency, generally regarded as being higher than 20 kHz.
ultrasonic impact grinding
A form of abrasive grinding in which a nonrotating tool vibrating at ultrasonic frequency causes a grit-loaded slurry to impinge on the surface of a workpiece, and thereby remove material. Compare with ultrasonic machining.
A nondestructive method in which beams of high-frequency sound waves are introduced into materials for the detection of surface and subsurface flaws in the material. The sound waves travel through the material with some attendant loss of energy (attenuation) and are reflected at interfaces. The reflected beam is displayed and then analyzed to define the presence and location of flaws or discontinuities. Most ultrasonic inspection is done at frequencies between 0.1 and 25 MHz–well above the range of human hearing, which is about 20 Hz to 20 kHz.
Material removal by means of the ultrasonic vibration of a rotating diamond core drill or milling tool. The process does not involve an abrasive slurry; instead, the diamond tool contacts and cuts the workpiece. Compare with ultrasonic impact grinding.
A soldering process variation in which high-frequency vibratory energy is transmitted through molten solder to remove undesirable surface films and thereby promote wetting of the base metal. This operation is usually accomplished without a flux.
See ultrasonic inspection.
A solid-state welding process in which materials are welded by locally applying high-frequency vibratory energy to a joint held together under pressure.
A crack in the heat-affected zone of a weld generally not extending to the surface of the base metal.
Same as supercooling.
A condition wherein a metal curves downward on leaving a set of rolls because of higher speed in the upper roll.
(1) In weldments, a depression on the face of the weld or root surface extending below the surface of the adjacent base metal. (2) A portion of a forging that has insufficient metal to give it the true shape of the impression.
Corrosion that occurs under organic films in the form of randomly distributed threadlike filaments or spots. In many cases this is identical to filiform corrosion.
Applying a cyclic stress lower than the endurance limit. This may improve fatigue life if the member is later cyclically stressed at levels above the endurance limit.
A state of stress in which two of the three principal stresses are zero. See also principal stress (normal).
(1) A type of corrosion attack (deterioration) uniformly distributed over a metal surface. (2) Corrosion that proceeds at approximately the same rate over a metal surface. Also called general corrosion.
The elongation at maximum load and immediately preceding the onset of necking in a tensile test.
The strain occurring prior to the beginning of localization of strain (necking); the strain to maximum load in the tension test.
A parallelepiped element of crystal structure, containing a certain number of atoms, the repetition of which through space will build up the complete crystal.
The net amount of power required during machining or grinding to remove a unit volume of material in unit time.
universal forging mill
A combination of four hydraulic presses arranged in one plane equipped with billet manipulators and automatic controls, used for radial or draw forging.
A rolling mill in which rolls with a vertical axis roll the edges of the metal stock between some of the passes through the horizontal rolls.
(1) The localized increase in cross-sectional area of a workpiece or weldment resulting from the application of pressure during mechanical fabrication or welding. (2) That portion of a welding cycle during which the cross-sectional area is increased by the application of pressure. (3) Bulk deformation resulting from the application of pressure in welding. The upset may be measured as a percent increase in interfacial area, a reduction in length, or a percent reduction in thickness (for lap joints).
A forging obtained by upset of a suitable length of bar, billet, or bloom.
The working of metal so that the cross-sectional area of a portion or all of the stock is increased. See also heading.
A resistance welding process in which the weld is produced, simultaneously over the entire area of abutting surfaces or progressively along a joint, by applying mechanical force (pressure) to the joint, then causing electrical current to flow across the joint to heat the abutting surfaces. Pressure is maintained throughout the heating period.